JP2004335615A - Metal oxide semiconductor, and manufacturing method and manufacturing apparatus thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively manufacture a metal oxide semiconductor and control characteristics of the metal oxide semiconductor in a wide range without using a complicated and expensive apparatus such as a sputtering system or an ion implanter. <P>SOLUTION: A metal oxide is embedded in powdery carbon. Subsequently, the metal oxide is subjected to heat treatment to release a part of oxygen in the metal oxide through an oxidation-reduction reaction, and an oxygen defect is generated in the metal oxide, thereby manufacturing the metal oxide semiconductor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a metal oxide semiconductor, an apparatus for manufacturing a metal oxide semiconductor, and a metal oxide semiconductor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when a metal oxide semiconductor is manufactured or its characteristics are improved, a metal oxide semiconductor is doped with a predetermined impurity element. For example, for a metal oxide such as ZnO and TiO _2, by adding Al as an impurity element, or to the appearance of semiconductor characteristics, and or to improve its properties.
[0003]
However, when such a conventional doping method is used, there is a problem that complicated and expensive devices such as a sputtering device and an ion implantation device are required, and a manufacturing process is complicated. In addition, the characteristics of the obtained metal oxide semiconductor are also limited by the type and amount of impurities to be doped, and there is a problem that a wide range of characteristics cannot be controlled.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to manufacture a metal oxide semiconductor at low cost without using a complicated and expensive device such as a sputtering device or an ion implantation device. Another object is to control the characteristics of a metal oxide semiconductor over a wide range.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides:
A step of embedding the metal oxide in powdered carbon,
Performing a heat treatment on the metal oxide to release a part of oxygen in the metal oxide through a reduction reaction, thereby generating an oxygen defect in the metal oxide to produce a metal oxide semiconductor. And a method for manufacturing a metal oxide semiconductor.
[0006]
Also, the present invention
The present invention relates to an apparatus for manufacturing a metal oxide semiconductor, comprising: a container filled with powdered carbon; and a heat treatment apparatus.
[0007]
In the present invention, a predetermined metal oxide is buried in powdered carbon so that the periphery of the metal oxide is in close contact with the carbon. When heat treatment is performed on the metal oxide in this state, the carbon exhibits high reducibility, so that an oxygen element is released from the metal oxide by a reduction reaction. As a result, oxygen vacancies are generated in the metal oxide, and accordingly, the metal oxide has semiconductor properties.
[0008]
That is, in the present invention, instead of the conventional sputtering device or ion implantation device, powdered carbon is used, and a sealed container for filling the same and a heat treatment device such as a commercially available electric furnace are simply prepared. Thus, a metal oxide semiconductor can be manufactured. Therefore, a metal oxide semiconductor can be manufactured at low cost.
[0009]
In addition, by appropriately controlling the heating temperature and the heating time in the above-described heat treatment, the amount of the oxygen vacancies can be freely adjusted, so that the semiconductor characteristics of the metal oxide semiconductor can be controlled over a wide range. Become like
Other features and advantages of the present invention are described in detail below.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a configuration diagram showing a part of the manufacturing apparatus of the present invention. In FIG. 1, a closed container 11 is prepared, and the inside thereof is filled with powdered carbon 12. The pyramid-shaped metal oxide 13 is disposed so as to be embedded in the carbon 12. As the closed container 11, a commercially available tamma tube can be used.
The container for filling the carbon 12 is not limited to the closed type, but may be an open type.
[0011]
The carbon 12 is required to be in a powder form in order to increase the contact area with the periphery of the buried metal oxide 13 and generate a sufficient reducing action on the metal oxide 13. Is not particularly limited. However, the average particle size of the carbon 12 is preferably 1.4 mm or less. Thereby, the contact area between the metal oxide 13 and the carbon 12 can be further increased, and the reduction action can be more effectively performed.
[0012]
The lower limit of the average particle size of the carbon 12 is not particularly limited, but is preferably 0.5 mm. Even if carbon having a lower particle size is used, the effect of the reducing action cannot be increased, and it becomes difficult to obtain and the handling becomes complicated.
[0013]
In the manufacturing method of the present invention, as shown in FIG. 1, a closed vessel 11 in which a metal oxide 13 is buried in carbon 12 is installed in a heat treatment apparatus such as an electric furnace, and a predetermined heat treatment is performed. Apply. The temperature of the heat treatment is not particularly limited as long as the above-described reduction action by the carbon 12 is sufficiently performed. However, the heat treatment is preferably performed at a temperature in the range of 800C to 1800C. Thus, the above-described reducing action can be sufficiently performed regardless of the type of the metal oxide 13 and the particle size of the carbon 12. Note that the heat treatment atmosphere can be set arbitrarily.
[0014]
Oxygen vacancies are formed in the metal oxide 13 through the above-described reduction action by the carbon 12, and as a result, semiconductor properties are exhibited according to the oxygen vacancies. A metal oxide semiconductor can be obtained.
[0015]
Thus, instead of the conventional sputtering apparatus or ion implantation apparatus, etc., the powdered carbon 12 is used, and the sealed container 11 for further filling the carbon 12 and a heat treatment apparatus such as a commercially available electric furnace are simply prepared. A metal oxide semiconductor can be manufactured. Therefore, the metal oxide semiconductor can be manufactured at low cost.
[0016]
In addition, by appropriately controlling the heating temperature and the heating time in the above-described heat treatment, the amount of the oxygen vacancies can be freely adjusted, so that the semiconductor characteristics of the metal oxide semiconductor can be controlled over a wide range. Become like
[0017]
Although the present invention can be applied to all kinds of metal oxides, it is particularly preferable to use it for metal oxides such as TiO ₂ , ZnO, MnO ₂ , Fe ₂ O ₃ and Fe ₃ O _4. Can be. As is clear from the above description, in the present invention, these metal oxides are doped with an impurity element without causing an oxygen deficiency due to the above-described reduction action of carbon, whereby semiconductor properties are improved. It is what causes. However, this does not completely exclude the doping of the impurity element.
[0018]
【Example】
A strip-shaped titanium plate (length 100 × width 3 × thickness 0.3 mm, purity 99.9%) is heat-treated in the air at a temperature of 900 ° C. for 110 hours, and is oxidized at a high temperature to obtain a plate-shaped titanium oxide. Was. In addition, it was confirmed that the titanium oxide was rutile type TiO ₂ and was a non-conductor.
[0019]
Next, the titanium oxide was placed in a closed container as shown in FIG. 1, and the periphery thereof was embedded with powdered carbon having an average particle size of 1.4 mm. Next, the closed container containing the titanium oxide was placed in an electric furnace and subjected to a heat treatment at five levels of 600 ° C., 800 ° C., 900 ° C., 1000 ° C., and 1100 ° C. for 30 minutes.
[0020]
FIG. 2 shows X-ray diffraction profiles of the titanium oxide before and after the heat treatment at 1000 ° C. As is clear from FIG. 2, after the heat treatment, the width of the peak caused by the rutile type TiO ₂ is widened, and oxygen is desorbed from the titanium oxide due to the reduction action by the powdered carbon, and oxygen deficiency is caused. It can be seen that the occurrence has occurred.
[0021]
FIG. 3 shows a graph of the temperature dependence of the electrical resistivity of the titanium oxide after the above-described heat treatment. At any temperature of 800 ° C., 900 ° C., 1000 ° C., and 1100 ° C., the electrical resistivity decreases as the measurement temperature increases, indicating that the titanium oxide exhibits semiconductor properties. In particular, at a temperature of 1100 ° C., a remarkable decrease in the electric resistivity was confirmed, and it was found that the material exhibited good semiconductor properties.
[0022]
Note that when the heat treatment at 900 ° C. was performed, the electrical resistivity increased at a temperature of 300 ° C. or more, and when the heat treatment at 1100 ° C. was performed, the electrical resistivity increased at a temperature of 500 ° C. or more. Can be This is considered to be because oxygen deficiency generated in titanium oxide through oxygen diffusion disappears during the measurement.
[0023]
FIG. 4 is a graph showing the temperature dependence of the output factor of the titanium oxide after the above-described heat treatment. At the temperatures of 800 ° C. and 900 ° C., the increase of the output factor was not confirmed at the temperature rise, but at the temperature of 1000 ° C., the increase of the output factor was confirmed with the rise of the temperature. confirmed.
[0024]
When heat-treated at 600 ° C., it did not exhibit semiconductor properties and remained in a non-conductive state.
[0025]
As described above, the present invention has been described based on the embodiments of the present invention while showing specific examples. However, the present invention is not limited to the above-described contents, and all modifications and changes may be made without departing from the scope of the present invention. Changes are possible.
[0026]
For example, in the above specific example, a closed container filled with powdered carbon in a closed container is prepared, and by installing a metal oxide in this container, the metal oxide is embedded in the powdered carbon. I am trying to be. However, the embedding of the metal oxide in the carbon is not limited to such an embodiment, and can be performed in any embodiment.
[0027]
【The invention's effect】
As described above, according to the present invention, a metal oxide semiconductor can be manufactured at low cost without using a complicated and expensive device such as a sputtering device or an ion implantation device, and characteristics of the metal oxide semiconductor can be reduced. A metal oxide manufacturing method, a metal oxide manufacturing apparatus, and a resulting metal oxide itself that can be controlled in a wide range can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a part of an apparatus for manufacturing a metal oxide semiconductor according to the present invention.
FIG. 2 shows an X-ray diffraction profile of the metal oxide semiconductor of the present invention.
FIG. 3 is a graph showing temperature dependence of electrical resistivity in a metal oxide semiconductor of the present invention.
FIG. 4 is a graph showing temperature dependence of an output factor in the metal oxide semiconductor of the present invention.
[Explanation of symbols]
11 Closed container 12 Powdered carbon 13 Metal oxide

Claims (10)

A step of embedding the metal oxide in powdered carbon,
Performing a heat treatment on the metal oxide to release a part of oxygen in the metal oxide through a reduction reaction, thereby generating an oxygen defect in the metal oxide to produce a metal oxide semiconductor. A method for manufacturing a metal oxide semiconductor. The method for producing a metal oxide semiconductor according to claim 1, wherein the average particle size of the carbon is 1.4 mm or less. The method according to claim 1, wherein the heat treatment is performed in a state where the metal oxide is loaded in a closed container and the carbon is filled so as to bury the metal oxide. 4. A method for manufacturing a metal oxide semiconductor. The method for manufacturing a metal oxide semiconductor according to claim 1, wherein the heat treatment is performed at a temperature of 800 ° C. to 1800 ° C. 4. The metal _oxide, TiO _{2, ZnO,} and wherein the at least one selected from the group consisting of MnO 2, _Fe 2 _{O 3} and _Fe 3 _{O 4,} according to any one of claims 1 to 4 A method for producing a metal oxide semiconductor. The method for producing a metal oxide semiconductor according to claim 1, wherein the metal oxide semiconductor does not contain a doping element. An apparatus for manufacturing a metal oxide semiconductor, comprising: a container filled with powdered carbon; and a heat treatment device. The apparatus for manufacturing a metal oxide semiconductor according to claim 7, wherein the average particle size of the carbon is 1.4 mm or less. A metal oxide semiconductor having oxygen vacancies and containing no doping element. TiO _{2, ZnO,} characterized in that it is composed of at least one selected from the group consisting of MnO 2, _Fe 2 _{O 3} and _Fe 3 _{O 4,} metal oxide semiconductor according to claim 9.

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